Process of making pigments.



UurTEr PATENT our- CE;

ANGEL EOFEATT, ZHDIANLlOLIS, INDIANA.

30 Brawl uz.

"Be itknown that Z, Axum Mon-3.1T. a citizen of'the United States,rcszdmg at Indianapolis, iu the county of-ltiarion and State of Indiana,have invented certain new and useful Improvements 1n Processes of MalnugPigments, of which the Iollowmg 1s a specification.

This invention relates to a process for the 19- production of animproved pigment, and

pcriazusparticularly-to a process which resuits in uv refined andsuperior quality of barium sulfate.

.The principal obgect, of mv invention is to x produce an extremelyfinely SUOCllYlClCd bunum sulfate 1n large quantities and m a verypurestate directly from the natural I mmeral barium sulfate.

It is a further obje t {0 reduce barium sul- 2 fate as above stated by aprocess cf fusion with a salt which is commercially abundant.

It, has long. been a well known, but heretofore an impracticable, factthat barium sulfate, when brouglitinto a condition of extremely finesubdivision, may then be cleared from all impurities, as it s the finetimaginable powder, and is not :fleeted bv' any known acid. It is alsowell known to .which results in What knownas? floated. or triple floatedbaf those familiar with the art that two classes 30 of pigments,produced by two inadequate and unsatisfactory methods are now derivedfrom natural barium known. as box-def,

T he firstmetbrxl is that XS commercially rytes, andicnnsists inmechanically pulverxzing to-as small a subdivision as: possible thenatural product, and then either sift-in or 40 flouting, m watertocollect the finest su (livisions of thepuwder, after which the latter isbleached and dried and sold in this state. However, the flout-ed barytcsthus produced, while possessing a sufiicicut degree of whiteness, hascomparatively no coveriug power or body, and is regarded generally as anudultcrorion. The second commercially used process consists inconverting the nut-oral mineral into barium sul- 59 fid, by'heaiiugwit-bcoal or other reducing material, then purifying and precipitating insolution, by some sulfate, generally sodium sulfate. The whiteprecipitate resulting therefrom is barium sulfate (chemically the comeas the original barrios), ;11-11d this sulfate, otherwise PROQZ'ESS OFMAKING PIGMENTS.

{ ter. .When purified, and separated partly either the wet; or dry formas dcsircd,the result is the blanc fixc. of well known commercialstandard. The latter, while being the best barytes pi ment. on themarket, is nevertheless unsatzsfhc-tory both as to its coverin abilityor opacity, and as to its ex: peuse 0 production. In pursuance of aperfect pigment of berium sulfate, which will have an ideal. body as apaint, and which will likewise be cheap, I have expended much time,effort and, expense, with the result to be hereinafter set forth andclaimed.

Generally speaking, my )roces s of treatment consists in fusing ormelting sodium sulfate, or any other slut-able salt. with bariumsulfate. until the latter enters into a complete state of solution oralloy with said salt and thereby becomes extremely finely subdivided.\Vhen the fused or melted mixture is cooled the salt, being a solubleone, may be dissolved away from the barium sulfate, which latter beinginsoluble will remain behind ina state of extreme subdivision, to beprements dictate. v

In the foregoin paragra h, and in the succeeding parts 0 my specication, I refer to the barium sulfate as being extremel finelysubdivided. This is a term which use to indicate the extreme subdivisionof tho barium. sulfate which I succeed in producing by my process, indistin ishin it' rom the ordinary owdered barium sulfate heretoforeproduced principal evidence of this extreme subdivision is found in theadequate and thorough product when used as a pamt pigment.

My preferred method of treating barium sulfate is as follows: I take thenatural form of barium sulfate (variously known under the names ofbarite, barytcs, heavy spar or tiff) and mix it suitably with sodiumsulfate, this being both an economical and eificient solvent for bariumsulfate and having a low fusing or melting pdfnt. The temperature oryoint, effusion of the mixture will be high or low accordiu to theproportion of sodium sulfate in te mixture and the proportion of sodiumsulfate is of sueh uantity that the two sulfates will beor salt S1llf&l9maybe in excess, so that. the

by other methods. The I m mo eculer proportion or the alkali sulfateprecipitate is purified by washing with waor .entirely from the water,for packing in pared for commerce in anyiorm, as requirccovering powerand complete oyacity of-my drawn and suitably cooled.

barium sulfate and sodium sulfate is heatmethod is used, the congealedproduct is my process, it is possible to use any of the j fused ormelted alloy will become homogeneous' at an early period. The mixture ofed in an appropriate vcssel until fusion occurs, and is maintained in astate of fusion until the alloy or solution is homogeneous or complete.U on. reaching this complete state. of alloy, tie fused mixture is with-The cooling process may be carried on either by pouring the mixture outto cool, or by pouring it into water in a gradual stream. -\Vhicheverthen boiled in water to dissolve the salt or alkali sulfate, and toprecipitate the barium sulfate. The water thus used, and containing thedissolved alkali sulfate is then removed for other use, preferably to beboiled i down to recover the alkali sulfate for future l re-use. Theprecipitate of barium sulfate l thus remaining, by reason of itsinsolubility in water, is the extremely finely subdivided productsoughtfor by my process. As a final step in its production, it issuitably treated by a process of washing and bleaching if desired. It iswashed in a water bath, to remove any impurities of a'solid nature whichmay remain, and may be treated with small quantities of acid to removeany coloring impurities. The purified barium sulfate may be drained anddried and suitably packed.

In the process of precipitation, it is possible to combine therewith thecooling step, by introducing the hot alloy in the fused state into thewater in a slow manner, thus causing the alloy to be prepared for theboiling and separating process in the same 5 vessel or apparatus inwhich it is cooled.

\Vhile I have specified the use of sodium sulfate as the solvent in thedescription of common salts to produce a solvent effect on bariumsulfate. However, practical experiments of an extended nature have shownsodium sulfate and potassium sulfate to be the most practicable andsatisfactory salts.

The result produced by the process above set forth is a pigment ofsuperior uality, especially suitable for use as a paint pigment.Extended experiment has disclosed the fact that a perfect pigment,chemically produced and nnilecularly subdivided in an exceptionally highdegree, may be supplied to enter commerce at a cost approximating$20.00.}3cr ton. This product is derived from the mineral ornaturalbarytcs or till, and is the result entirely of the proccss hercinbel'oredescribed. its cost of production is small, by reason of the comparativesimplicity, and case of installation, of the apparatus necessary, and byreason of the general C(Hnlllttlrifll quantities i! which the necessarysolvent can be obtained.

It is evident, therefore, that I may pro duce by my new method a bariumsulfate which has a completcr body or covering power, and which may beproduced in quantities more nearly approaching an adequate commercialutility than has heretofore been possible, thereby realizing the objectof chemists, artists, and those commercially interested in paintpigments of this charfate with an alkaline sulfate, and precipitatingthe barium sulfate from the alkaline sulfate.

2. A process of producing barium sulfate in an extremely fine state ofsubd'vision, which consists in fusing natural barium sulfate witlranalkaline sulfate, cooling the fused mass, and dissolving the alkalinesulfate from the barium sulfate in water.

3. A process of producing barium sulfate in a state of extremely finesubdivision which consists in fusing natural barium sulfate with sodiumsulfate, and dissolving thesodium' sulfate from the barium sulfate inwater.

In testimony whereof I have atlixed m signature in presence of twowitnesses.

ANSIL MOFFATT. J

Witnesses:

EDWARD A. Loan, \VJLLIAM C. Buss.

